[Calcium and bone metabolism across women's life stages. The effects of oral contraceptives/low dose estrogen-progestin on bone metabolism, bone mass and geometry in adolescent and young adult women.]

Estrogens have a biphasic action on pubertal and/or adolescent skeletal growth. Low levels of estrogen may increase the periosteal expansion through the increase in the sensitivity of bone for mechanical stimuli and the secretion of IGF-1. On the other hand, high estrogen concentrations may inhibit periosteal bone formation. To use OC/LEP(oral contraceptive/low dose estrogen-progestin) during adolescence, meaning exposure to high levels of estrogen, may prevent the acquisition of physiologic peak of bone mass.